Trading kidneys, repugnant markets and stable marriages win the Nobel Prize in Economics

Roth and Shapley charted a course for economists to go beyond simply arguing for markets in everything.

The 2012 Nobel Prize in Economics - technically the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel, but nobody cares - has been awarded to two American Economists, Alvin Roth and Lloyd Shapley "for the theory of stable allocations and the practice of market design". The Nobel Committee explains what that means:

This year's Prize concerns a central economic problem: how to match different agents as well as possible. For example, students have to be matched with schools, and donors of human organs with patients in need of a transplant. How can such matching be accomplished as efficiently as possible? What methods are beneficial to what groups? The prize rewards two scholars who have answered these questions on a journey from abstract theory on stable allocations to practical design of market institutions.

Lloyd Shapley used so-called cooperative game theory to study and compare different matching methods. A key issue is to ensure that a matching is stable in the sense that two agents cannot be found who would prefer each other over their current counterparts. Shapley and his colleagues derived specific methods – in particular, the so-called Gale-Shapley algorithm – that always ensure a stable matching. These methods also limit agents' motives for manipulating the matching process. Shapley was able to show how the specific design of a method may systematically benefit one or the other side of the market.

Alvin Roth recognized that Shapley's theoretical results could clarify the functioning of important markets in practice. In a series of empirical studies, Roth and his colleagues demonstrated that stability is the key to understanding the success of particular market institutions. Roth was later able to substantiate this conclusion in systematic laboratory experiments. He also helped redesign existing institutions for matching new doctors with hospitals, students with schools, and organ donors with patients. These reforms are all based on the Gale-Shapley algorithm, along with modifications that take into account specific circumstances and ethical restrictions, such as the preclusion of side payments.

Even though these two researchers worked independently of one another, the combination of Shapley's basic theory and Roth's empirical investigations, experiments and practical design has generated a flourishing field of research and improved the performance of many markets. This year's prize is awarded for an outstanding example of economic engineering.

The committee have yet again reaffirmed the old adage that the most important thing to do when trying for a nobel prize is to live long enough that your achievements are recognised. The Gale-Shapley algorithm, for instance, was devised in 1962, when Lloyd Shapley was 34. It concerns a maths problem known as the stable marriage problem: if you have an even number of men and women, can you always come up with a set of marriages where there are no two people of opposite sex who would both rather have each other than their current partners? (1960s maths problems: usually heteronormative.) If you can, then the marriage is "stable".

The Gale-Shapley algorithm is a way of always ensuring stable matches; and much of Shapley's work covers the same areas, straddling the boundaries between economics, mathematics, and computer science.

Roth is the younger of the two winners, and works in a far more empirical sphere. As the committee points out, although the two men never actually collaberated, Roth took Shapley's theoretical work and applied it to actually existing markets. For instance, Roth used the Gale-Shapley agorithm to ease the kidney shortage in the US. David Wessel explains (£):

As of noon yesterday, 58,470 people in the U.S. were waiting for a kidney transplant. Most won't get one this year. There aren't enough donated kidneys to go around. Surgeons transplanted just 15,129 kidneys last year. Now a band of transplant surgeons and economists are trying to fix that by creating a moneyless market for exchanging kidneys. Most transplanted kidneys come from a person who has died, a supply that grows slowly because of ignorance about the need for donations or grieving relatives' reluctance. But a kidney taken from a live donor works better, and almost everyone has a spare. As techniques improve for removing healthy kidneys and for suppressing the body's tendency to reject a transplant, doctors increasingly turn to kidneys from living donors, usually relatives. Last year, 43% of kidneys transplanted in the U.S. came from living donors, up from 28% a decade ago. But a biological barrier often blocks a transplant from a relative. In about a third of all would-be pairs, blood types are incompatible. In others, the sick person has antibodies that can initiate a rejection of the donated organ. It's heartbreaking "to have the treasure of the live donor and then have that not go forward because of a biological obstacle," says Massachusetts General Hospital transplant surgeon Francis DelMonico.

Occasionally, transplant centers spot a way out: One New England father with blood type A couldn't donate a kidney to his daughter with blood type B. So he gave a kidney to a teenager with blood type A, and the teenager's sister gave a kidney for the man's daughter. New England's transplant centers have done six such exchanges. Baltimore's Johns Hopkins University has done seven.

The crucial thing about Roth's work, from an economic point of view, is that it involves finding stable allocations using market-like situations without involving money. The kidney swaps in the New England situation are market-like, trading kidneys for kidneys in a way that makes all parties better-off, but they don't actually require kidneys to be bought and sold.

We can see the importance of this by looking at another paper of Roth's, not cited by the committee, on repugnance in markets (pdf). Roth demonstrates that some markets are limited because the very existance of a market in some goods is considered repugnant. He argues, for instance, that the trade in horse meat being banned in California is not done through fears that eating horse meat is unsafe; nor is it done for animal welfare reasons, since it is still legal to farm and kill horses. But banned it is, and Roth argues that the natural response of economists to situations of this type - to argue for freer markets - is wrong, since it ignores the very strong feelings involved in the situation. Instead:

Being aware of the sources of repugnance can only help make such discussions more productive, not least because it can help separate the issues that are fundamentally empirical—like the degree of crowding out of altruistic donations that might result from different incentive schemes compared to how much new supply might be produced—from areas of disagreement that are not primarily empirical.

Hopefully his new Nobel Prize should give that argument greater weight in the years ahead.

A patient receives a kidney in Johns Hopkins university in Baltimore. Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

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Find the EU renegotiation demands dull? Me too – but they are important

It's an old trick: smother anything in enough jargon and you can avoid being held accountable for it.

I don’t know about you, but I found the details of Britain’s European Union renegotiation demands quite hard to read. Literally. My eye kept gliding past them, in an endless quest for something more interesting in the paragraph ahead. It was as if the word “subsidiarity” had been smeared in grease. I haven’t felt tedium quite like this since I read The Lord of the Rings and found I slid straight past anything written in italics, reasoning that it was probably another interminable Elvish poem. (“The wind was in his flowing hair/The foam about him shone;/Afar they saw him strong and fair/Go riding like a swan.”)

Anyone who writes about politics encounters this; I call it Subclause Syndrome. Smother anything in enough jargon, whirr enough footnotes into the air, and you have a very effective shield for protecting yourself from accountability – better even than gutting the Freedom of Information laws, although the government seems quite keen on that, too. No wonder so much of our political conversation ends up being about personality: if we can’t hope to master all the technicalities, the next best thing is to trust the person to whom we have delegated that job.

Anyway, after 15 cups of coffee, three ice-bucket challenges and a bottle of poppers I borrowed from a Tory MP, I finally made it through. I didn’t feel much more enlightened, though, because there were notable omissions – no mention, thankfully, of rolling back employment protections – and elsewhere there was a touching faith in the power of adding “language” to official documents.

One thing did stand out, however. For months, we have been told that it is a terrible problem that migrants from Europe are sending child benefit to their families back home. In future, the amount that can be claimed will start at zero and it will reach full whack only after four years of working in Britain. Even better, to reduce the alleged “pull factor” of our generous in-work benefits regime, the child benefit rate will be paid on a ratio calculated according to average wages in the home country.

What a waste of time. At the moment, only £30m in child benefit is sent out of the country each year: quite a large sum if you’re doing a whip round for a retirement gift for a colleague, but basically a rounding error in the Department for Work and Pensions budget.

Only 20,000 workers, and 34,000 children, are involved. And yet, apparently, this makes it worth introducing 28 different rates of child benefit to be administered by the DWP. We are given to understand that Iain Duncan Smith thinks this is barmy – and this is a man optimistic enough about his department’s computer systems to predict in 2013 that 4.46 million people would be claiming Universal Credit by now*.

David Cameron’s renegotiation package was comprised exclusively of what Doctor Who fans call handwavium – a magic substance with no obvious physical attributes, which nonetheless helpfully advances the plot. In this case, the renegotiation covers up the fact that the Prime Minister always wanted to argue to stay in Europe, but needed a handy fig leaf to do so.

Brace yourself for a sentence you might not read again in the New Statesman, but this makes me feel sorry for Chris Grayling. He and other Outers in the cabinet have to wait at least two weeks for Cameron to get the demands signed off; all the while, Cameron can subtly make the case for staying in Europe, while they are bound to keep quiet because of collective responsibility.

When that stricture lifts, the high-ranking Eurosceptics will at last be free to make the case they have been sitting on for years. I have three strong beliefs about what will happen next. First, that everyone confidently predicting a paralysing civil war in the Tory ranks is doing so more in hope than expectation. Some on the left feel that if Labour is going to be divided over Trident, it is only fair that the Tories be split down the middle, too. They forget that power, and patronage, are strong solvents: there has already been much muttering about low-level blackmail from the high command, with MPs warned about the dire influence of disloyalty on their career prospects.

Second, the Europe campaign will feature large doses of both sides solemnly advising the other that they need to make “a positive case”. This will be roundly ignored. The Remain team will run a fear campaign based on job losses, access to the single market and “losing our seat at the table”; Leave will run a fear campaign based on the steady advance of whatever collective noun for migrants sounds just the right side of racist. (Current favourite: “hordes”.)

Third, the number of Britons making a decision based on a complete understanding of the renegotiation, and the future terms of our membership, will be vanishingly small. It is simply impossible to read about subsidiarity for more than an hour without lapsing into a coma.

Yet, funnily enough, this isn’t necessarily a bad thing. Just as the absurd complexity of policy frees us to talk instead about character, so the onset of Subclause Syndrome in the EU debate will allow us to ask ourselves a more profound, defining question: what kind of country do we want Britain to be? Polling suggests that very few of us see ourselves as “European” rather than Scottish, or British, but are we a country that feels open and looks outwards, or one that thinks this is the best it’s going to get, and we need to protect what we have? That’s more vital than any subclause. l

* For those of you keeping score at home, Universal Credit is now allegedly going to be implemented by 2021. Incidentally, George Osborne has recently discovered that it’s a great source of handwavium; tax credit cuts have been postponed because UC will render such huge savings that they aren’t needed.

Helen Lewis is deputy editor of the New Statesman. She has presented BBC Radio 4’s Week in Westminster and is a regular panellist on BBC1’s Sunday Politics.

This article first appeared in the 11 February 2016 issue of the New Statesman, The legacy of Europe's worst battle